TE21 waveguide converter has been widely applied in many fields, such as the generating microwave sources based on the interaction between the electron beam and TE21 waveguide mode; in R&D of plasma heating, circularly polarized TE21 mode is the best choice for generating symmetrical plasma; in application of antenna, TE21 mode could emit and receive differential signals with enhanced navigation.
There are two common methods for using cylindrical waveguide to generate TE21 mode, one is spiral/wave structure, and another is porous sidewall coupling. The former uses a deformed waveguide structure to gradually convert the wave to the desired mode; the conversion duration is long and different modes could be converted. The latter use a long and straight waveguide, which sidewall contains many coupling holes. Similar to the spiral converter, this type of converter requires longer conversion components and allows electric wave to convert to desired mode gradually. The surplus electric wave generated in the conversion process could affect the electron beams, and result in serious mode competition problem. Therefore, enhancing the conversion efficiency and improving the mode purity could prevent complicated mode competition problem.
Thus, to overcome the aforementioned problems of the prior art, it would be an advancement if the art to provide a polarized high-order mode electromagnetic wave coupler and its coupling method, which allows the coupler to have high conversion efficiency, high mode purity, broad bandwidth, polarized controllability, and simplified structure.
To this end, the inventor has provided the present invention of practicability after deliberate design and evaluation based on years of experience in the production, development and design of related products.